The reciprocal interaction between influenza virus and host microRNAs (miRNAs) has been implicated in the regulation of viral replication and host tropism. However, the global roles of the cellular miRNA repertoire and the mechanisms of miRNA-mediated antiviral defense await further elucidation. In this study, we systematically screened 297 cellular miRNAs from human and mouse epithelial cells and identified five inhibitory miRNAs that efficiently inhibited influenza virus replication in vitro and in vivo. Among these miRNAs, hsa-mir-127-3p, hsa-mir-486-5p, hsa-mir-593-5p, and mmu-mir-487b-5p were found to target at least one viral gene segment of both the human seasonal influenza H3N2 and the attenuated PR8 (H1N1) virus, whereas hsa-miR-1-3p inhibited viral replication by targeting the supportive host factor ATP6V1A. Moreover, the number of miRNA binding sites in viral RNA segments was positively associated with the activity of host miRNA-induced antiviral defense. Treatment with a combination of the five miRNAs through agomir delivery pronouncedly suppressed viral replication and effectively improved protection against lethal challenge with PR8 in mice. These data suggest that the highly expressed miRNAs in respiratory epithelial cells elicit effective antiviral defenses against influenza A viruses and will be useful for designing miRNA-based therapies against viral infection.

流感病毒和宿主微RNA（miRNA）之间的相互相互作用已牵涉到病毒复制和宿主嗜性的调控中。但是，细胞miRNA的全部功能以及miRNA介导的抗病毒防御的机制尚待进一步阐明。在这项研究中，我们系统地筛选的297倍细胞的miRNA来自人类和小鼠的上皮细胞和确定了五个抑制的miRNA能够有效地抑制流感病毒复制在体外和体内。在这些miRNA中，发现hsa-mir-127-3p，hsa-mir-486-5p，hsa-mir-593-5p和mmu-mir-487b-5p靶向两个人类的至少一个病毒基因片段季节性流感H3N2和减毒PR8（H1N1）病毒，而hsa-miR-1-3p通过靶向支持性宿主因子ATP6V1A抑制病毒复制。此外，病毒RNA片段中miRNA结合位点的数量与宿主miRNA诱导的抗病毒防御的活性呈正相关。通过agomir递送使用这五个miRNA的组合进行的治疗显着抑制了病毒复制，并有效提高了小鼠抗PR8致死性攻击的保护能力。